sodium amidotrizoate

Diatrizoic acid (or its anionic form, diatrizoate), also known as amidotrizoic acid, or 3,5-diacetamido-2,4,6-triiodobenzoic acid, is a radiocontrast agent containing iodine. Trade names include Hypaque, Gastrografin, Iothalmate and Urografin, the latter being a combination of the sodium and meglumine salts.
Diatrizoate is considered a high-osmolality contrast agent. Its osmolality ranges from approximately 1500 mOsm/kg (50% solution) to over 2000 mOsm/kg (76% solution).